Page 200 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 176

[ ] Well Programming
2.3.3

than the formation, the easiest route is for the bit to come off the plug.
Monitor the returns for formation cuttings; if progress is too fast to
monitor progress properly then drill around 10 ft and circulate for
samples before continuing. An inclination survey (Totco or
Anderdrift) can be compared to the original inclination at that depth
to confirm that the well was kicked off.
Once all the returns are formation cuttings with little or no
cement, drill ahead with reduced WOB and reaming two or three
times before making a connection to allow the well to start dropping
angle towards vertical. When the inclination is satisfactory a locked
assembly can be run, carefully reamed through the kickoff depth and
drilling ahead continued.
This technique would only be viable where it did not matter on
which side the well kicked off. If the downhole target was large or
close enough then this could be considered. Since no downhole motor
or MWD is required, this could be a low-cost option in the right cir-
cumstances. See “Kickoff plugs” in Section 2.7.5, “Cementing Design
for Cement Plugs and Squeezes.”
Kicking off in casing from a window (direction controlled). A
well may be kicked off from inside casing for various reasons, such as
to reuse a nonproductive well by drilling to a new target, collapsed
casing lower down, etc. A whipstock in casing method is described
below, but a window can also be milled in the casing and the well can
be kicked off in a cement plug set across the window.
Run a casing mill to the desired depth. The length of window
required will vary with the casing size and the expected dogleg sever-
ity that can be obtained with the motor and bent sub or bent housing.
Mill a window of the desired length. Set a cement plug from about
100 ft below the window to about 20 ft above.
Run in with the directional motor assembly and tag the top of the
cement carefully while circulating and rotating slowly. Drill off the
cement to the top of the window. Orientate the motor in the desired
direction and commence the kickoff.
Kicking off in casing with a whipstock. A whipstock is basically
a long wedge-shaped metal guide that is run in attached to the BHA
and set on bottom, oriented in the direction of desired kickoff. The
whipstock is held in place on the milling assembly by a shear bolt;
once oriented (checked by a single shot survey run to a UBHO sub)

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